Visible crew/equipment: When Fred kisses Peggy, a boom mic is reflected in the left side of the car.
Continuity mistake: When the inebriated cuckoo pops out of the cuckoo clock at the beginning of the short, his feet are yellow, but when we see a close-up of the cuckoo in the next shot, his feet are now orange.
Continuity mistake: When Tom picks up a telephone book, you can see he is holding the book with both hands, but when we see a close-up of the "Ajax Mouse Exterminators" in the next shot, his hands are nowhere to be seen.
Audio problem: When Bugs says "That's the old ginger, boy!" when practising with his baseball bat, his mouth doesn't move.
Factual error: When the camera pans to the theatre right after the opening credits, the sign uses the British spelling of "theatre" instead of the American "theater."
Continuity mistake: The plot is based on obtaining 3 music boxes, identical in appearance each playing a slight variation of the same tune. Throughout the movie the variations are highlighted as a message is revealed by listening to all 3 variations. Yet at the beginning of the movie when the boxes are all sold at the same auction, when each box is presented, the tune had no variations.
Continuity mistake: The postman hangs his bag to the hook on the wall. By the noise, he knows a split-second in advance that an explosion is about to happen, and ducks. The actor ducks out of view; we are not supposed to notice that once he disappears, film editing inserts the part when the background partially detonates. We however do, because the bag in the foreground changes position in the space of a single frame. (00:05:25)
Continuity mistake: When Bugs kisses the mechanical rabbit, the rabbit short-circuits and breaks into pieces onto the floor. Bugs then starts to leave, but when the scientist pushes Bugs back to meet the monster, the pieces have disappeared.